Generally, a vehicle has a lighting system for the providing a lighting function so that a driver may observe matters in the driving direction in a better way when driving at night and for informing other vehicles or passengers of a driving status of the vehicle. A head lamp, also called a headlight, is a lamp for lighting a forward path as a vehicle advances, and the head lamp is required to have brightness allowing a driver to check an obstacle on a road, 100 meters from the vehicle at night. The standards of such a head lamp vary depending on countries. Particularly, the head lamp beam may irradiate is various directions depending on whether traffic must keep to the right or to the left.
An existing head lamp for a vehicle provides a fixed lighting pattern regardless of road circumstances or situations which may change in various environments. Therefore, a suitable sight may not be ensured when driving fast or in the country where long-distance sight line is needed, when driving in an city setting where the level of reliance on the brightness of the head lamp is relatively low, and when driving in a bad weather where the road wet by rain or snow dazzles or temporarily blinds thereby reducing the sight of the driver.
An adaptive front lighting system (AFLS) has been introduced so that a driver and an opponent or oncoming driver may recognize the front, light or oncoming vehicle more easily. The AFLS is a system which changes width and length of a headlight beam according to driving conditions of a vehicle, road conditions, environmental conditions, and the like. For example, when a vehicle corners slowly at a turn in the road, the AFLS may turn on an additional light. In addition, the brightness of the head lamp may be adjusted so that a driver of a vehicle approaching in the opposite direction may not be dazzled.
In particular, as shown in FIG. 1, there are regulations regarding the intensity of illumination and irradiating range of a high beam and a low beam of right and left head lamps installed on a vehicle for safe driving. The horizontal axis in the graph represents a forward horizontal line, and the vertical axis represents a light axis. The right and left head lamps based on the forward horizontal line represent a right and left angle of an irradiated light distribution region, and the lighting axis which is the vertical axis represents an upper and lower angle. In particular, three regions depicted at the lower end portion of the forward horizontal line have an important meaning in the light distribution regulations. The region marked by Emax is a light distribution region for ensuring a sight about road information, passenger location and passenger information. The region of Segment 10 and 20, located at the lower end portion of Emax, is biased toward an oncoming vehicle on the left from the light axis in comparison to the Emax region. Particularly, when driving in wet weather, the Segment 20 is a light distribution region influencing the sight of a driver of an oncoming vehicle or a preceding vehicle due to reflective glare since the light irradiated from the head lamps are refracted by raindrops falling at the front and/or the reflective surface of water formed on the road by the rain.
Therefore, a so-called in-rain driving mode which prevents the lead lamp of a vehicle from irradiating light to a front region adjacent to the head lamp is demanded. For example, a head lamp assembly which may irradiate light in a class W pattern among various head lamp lighting patterns is desirable. Such a beam pattern for a special light distribution region should satisfy maximum and minimum intensity of illumination regulated by the laws, as shown in FIG. 2. The illumination regulations shown in FIG. 2 represent, for example, maximum and minimum intensity of illumination of a beam pattern of class W, which should be obeyed for vehicles exported to the Europe.
For example, the 18th item “Emax” in the light distribution laws of FIG. 2 requires a higher illumination range (21875 to 50000 candela) in comparison to other light distribution regions so that a driver may surely recognize front road information and right sidewalk information to decrease sudden traffic accidents. In addition, the region of Segment 10 and 20 associated with dazzling of an oncoming vehicle in the rain requires intensity of illumination not higher than 5000 candela or 12500 candela so that dazzling is minimized toward an oncoming vehicle.
Therefore, it is desirable to provide a system which may allow a driver and an opponent driver to recognize the area in front in a better way while satisfying intensity of illumination and light distribution regulated by the laws, by providing a head lamp generating a suitable beam pattern depending on varying road conditions and weather situations.
As described above, the regulations in relation to class W should be satisfied in order to prevent traffic accidents which may occur due to dazzling in the rain. As shown in FIG. 1, the Emax region which should have the maximum brightness and the region of Segment 20 which should have low intensity of illumination to prevent dazzling of an oncoming vehicle in the rain are very adjacent to each other. Therefore, it is technically difficult to fabricate a head lamp assembly satisfying both conditions.
In this regard, in the related art, there has been disclosed a configuration where an additional light intercepting structure B is further provided above an existing light intercepting structure A to selectively intercept the light irradiated forwards, as shown in FIG. 3.
However, since the in-rain driving mode should have a separate light intercepting structure, process costs and construction time increase due to the added component. In addition, as shown in FIG. 4, since the light irradiated forwards is intercepted by the additional light intercepting structure B, a region C where light is not irradiated is generated, which greatly deteriorates observability to the road surface in the front, thereby increasing the risks of traffic accidents.